#include<stdio.h>

int main()
{
	char ch;
	printf("input  character :\n");
	scanf("%c",&ch);
	if(ch>='A'&&ch<='Z')
	{
		ch = ch + 32;
		printf("%c",ch);
	} 
	else if(ch>='a'&&ch<='z')
	{
		ch = ch - 32;
		printf("%c",ch);
	}
	else 
	printf("input error!");
	return 0;
}
